Depositional and tectonic relationships of upper ordovician and lower silurian strata around dinas mawddwy, mid-wales
✍ Scribed by D. M. D. James
- Book ID
- 102846300
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 885 KB
- Volume
- 26
- Category
- Article
- ISSN
- 0072-1050
No coin nor oath required. For personal study only.
✦ Synopsis
The field evidence for the lateral impersistence of the Garnedd-wen Formation (Hirnantian) and Derwen Formation (Aeronian) immediately northeast of Dinas Mawddwy is reviewed and the evidence for strike faulting as inferred by W. J. Pugh (1928) is reassessed. It is concluded that little if any strata are missing and that surfaces of non-deposition, rather than fault cut-out, better explain any strata that are locally abnormally thinned. However strike faulting is newly proven west of Dinas Mawddwy and accounts for much of the rapid apparent thickness variation in the Broad Vein (Rawtheyan) there. The newly constrained thickness estimates strongly imply that sedimentation was influenced by a basement fracture at Dinas Mawddwy. Structural reasoning and palaeocurrent evidence from the Garnedd-wen Formation suggest that this fracture probably parallels the Corris-Lfangranog fracture to the southwest.